The more one descended into the Black Prison, the fewer criminals there were and the higher their strengths.

Gu Zuo had already come to the second to the last floor. Here there were pharmacists and Xiantian stage eight or Immortal Realm martial artists who'd committed great evil. The ones locked up in the deepest parts of the Black Prison were martial artists at the Immortal Realm or stronger.

Gu Zuo could understand the others, but why would pharmacists be kept here? He was a bit unclear about it — Could it have been because pharmacists were even more precious?

Because he had these misgivings, he just asked Elder Huo.

Elder Huo's expression suddenly became somewhat complicated: "Student Gu, you're still too young and your nature is upright, so you wouldn't understand the inferences… Look."

According to Elder Huo's words, Gu Zuo turned his head and looked at the explanation on the nearest pharmacist's cage.

His eyes instantly widened.

[Lu You, a low-level pharmacist who discovered a type of Wondrous Poison. In order to test its toxicity, he used a small nation as test subjects, causing the deaths of three by ten thousand by ten thousand people countrywide. Because the outcome brought about was excessively evil, the country's survivors appealed to the Qingyun Sect. The Sect's Core Disciple Fang Yunwen and Pharmacist Hall's mid-level pharmacist Qu Xing acted together to capture him and eliminate the remaining poison. Because the country had already become a dead land, even though the remaining poison was purged, it hasn't recovered its life force to this day.]

Three by ten thousand by ten thousand people!

— Wasn't that three hundred million?

Gu Zuo took a deep breath.

During the modern era, even the country purported to have the greatest population had no more than 1.8 billion people. But Lu You, this low-level pharmacist, unexpectedly poisoned as many as one sixth of that!

Too terrifying! It was also too horrendous…

At this time, Gu Zuo understood at last.

The so-called Black Prison distributed its prison cells and floors based on danger levels. One shouldn't look at pharmacists and see that their martial strength was nothing special. Their harmfulness was much greater than that of martial artists, especially the sort like Lu You, who could wantonly poison others for a new discovery. The evils committed by a single person could rival ten million "extremely vicious and evil" martial artists!

The Black Prison acted as a storage warehouse for live specimens. Presumably, it also had a strong relationship with the danger levels of the pharmacists it harbored. With live specimens, those pharmacists who wanted to research or attempt something would have a way to do so.

Gu Zuo's heart was a little distressed.

He certainly wouldn't commit such deranged things… However, "scientists" were frightening.

Ah, it was scary to think about it.

As he walked to the interior, Gu Zuo discovered that there really were many pharmacists locked up here. In other words, there were many people who conducted dangerous experiments that went against heaven and reason. He sighed, not the least bit sympathetic for them.

The pursuit of truth and the desire to do research was fine, but doing so in excess was out of the question. Because things such as this and all sorts of evil acts were equally undeserving of forgiveness.

Gu Zuo calculated his remaining contribution points, and picked three people.

Individually, there was a Xiantian stage two, a Xiantian stage five, and a Xiantian stage seven pharmacist. Because they were each low, mid, and high-level pharmacists, the spent contribution points totaled to about one thousand four hundred. In addition, he also took a Xiantian stage eight martial artist.

Buying that many people consisting of martial artists and pharmacists cost close to four thousand contribution points. Besides the three thousand that the Steadfast Heart Pill netted him, he also had close to a thousand additional points. These were from him mending several other prescriptions.

Unfortunately, although he had obtained contribution points that countless Inner Sect disciples would never have been able to acc.u.mulate, he spent the "money" like flowing water. In just a brief period of time, he only had a hundred points left to use.

After Elder Huo led Gu Zuo to the medicine refining rooms in the depths of the Black Prison, he told Gu Zuo: "Each medicine refining room requires five contribution points to be rented for a day. There are many top-notch facilities inside, and there's also an Earth Fire you can use. When staying inside for a day, your disciple token's contribution points will automatically be deducted. If you exceed the limits of your contribution points, no matter what tests you're doing, the doors will be opened. Thus, this student must always remember to not waste your time. Otherwise, the process of your experiment will be exposed to the eyes of those who come in front of the opened door."

Naturally, Gu Zuo promptly thanked him again for the reminder.

At this time, after Elder Huo warned Gu Zuo about some important matters, he finally left — After all, Gu Zuo would be researching for a long time, and he had many secrets. Elder Huo couldn't be allowed to follow Gu Zuo and wait for him here, right?

Despite it being like this, Gu Zuo still repeatedly thanked him. He trailed Elder Huo with his eyes until he was far away.

Afterwards, Gu Zuo went to pick a room.

Generally speaking, if there wasn't a disciple token inserted in the door, it was unoccupied, and if there was a token inserted, it was occupied. As he traveled along the pitch-black alley, he found that there wasn't any difference between the designs of the medicine refining rooms and the Black Prison. It seemed very foreboding.

However, it was still much more popular than what Gu Zuo imagined. After walking for at least dozens of meters, the medicine refining rooms on both sides were all surprisingly occupied. It went to show that the pharmacists in the Qingyun Sect all had very strong mindsets towards research!

As he walked to the end of the alley, he still hadn't found a room. Gu Zuo turned the corner, intending on finding one along another alley. But just as he turned the corner, he heard footsteps ahead.

Clack, clack, clack…

In this quiet place, it seemed particularly clear.

Gu Zuo raised his head to look.

That person walked closer and closer… Suddenly, he opened his mouth: "Are you?"

Gu Zuo stared blankly: "You are, uh, Senior Sect Brother Xu?"

Correct, the one who was approaching him was precisely Xu Lingxiu!

It hadn't been long since they parted ways before meeting again here.

Oh, it truly was…a curious coincidence.

Xu Lingxiu still had that haughty appearance as he looked Gu Zuo up and down: "What did you come here to do?"

Gu Zuo forced a laugh: "To verify a type of toxin I found…"

Xu Lingxiu raised his chin: "You exchanged contribution points for this?"

Gu Zuo naturally nodded: "Yes."

Xu Lingxiu harrumphed: "In honor of you giving me that prescription… Alright, take it."

While he spoke, he casually threw something over.

Gu Zuo knew about this young master's temperament and immediately used both hands to catch it. After that, he felt the blazing temperature of the thing in his palms — Although it wouldn't burn his hands, it was very hot.

Xu Lingxiu said: "A Fire Essence Stone. Does a country b.u.mpkin like you know of it?"

Gu Zuo thought about it, and his eyes shined: "It raises an Earth Fire's rank?"

Xu Lingxiu lifted his chin again: "Correct. Consider this me having pity on you, peasant!"

Following that, he turned around and inserted his disciple token directly into a crack in the wall. His mouth still didn't forget to throw out a sentence: "When you're doing your experiment, you can't do things haphazardly. You'll be throwing your little life away!"

Then his figure disappeared into that doorway.

Gu Zuo looked at the stone doors that were already tightly closed. Then he looked at the Fire Essence Stone in his hands again. He was truly flabbergasted.

Since the item book that introduced Earth Fires also mentioned lots of Wondrous Fires, it naturally mentioned how to cultivate the Wondrous Fires. The Fire Essence Stone was a type of ore that had the greatest use for Earth Fires. One would directly throw it into an Earth Fire, and it could briefly raise the Earth Fire's rank before it finished burning — For example, a rank five Earth Fire could be raised to rank four, a rank four could be raised to rank three, and so on. Merely, there were differences in the product grades of the Fire Essence Stones thrown in.

The piece that Xu Lingxiu gave Gu Zuo was the kind that raised a rank five Earth Fire to rank four.

Gu Zuo got this thing. If he wanted to refine poisonous medicinal pills, it would be more suitable to use an Earth Fire with a higher rank. After lamenting the young master's pride and can-do behavior at the bottom of his heart, he continued to find a room.

— This time around, his luck was good.

It wasn't but a few paces away. There was a certain room about two or three rooms adjacent to Xu Lingxiu that didn't have a disciple token. Gu Zuo's heart was happy as he directly inserted his own disciple token into it.

The door opened.

It was completely empty inside. Besides the pit of an Earth Fire, there was only an ordinary large-scale pill cauldron. There wasn't too big a difference between its appearance and that of the Earth Fire Rooms. However, the area was very expansive.

Gu Zuo could see that the fringes also had some marks of abraded metal. This was —

He quickly realized what this was.

After the sound of grinding gears echoed, the ground where those marks were located split open. Immediately following that, eleven metal berths rose up from below.

On each metal berth was a heavily shackled person.

There were martial artists, and there were also pharmacists…

These were the test subjects Gu Zuo had bought.

All of the live specimens on the metal berths had their eyes blindfolded.

Most of their bodies, which had been in long-term captivity, appeared wan. Their qi and blood had also been heavily eroded. However, their true qi and realms hadn't shown any changes. The Black Prison guaranteed the continuation of their lives.

Gu Zuo's thoughts turned. A handful of multi-colored, mutated Scarlet Blood Rice appeared on a table nearby. He cautiously took out a gray-colored grain. After cutting it open, he consumed a single measured drop.

Afterwards, he began cutting open the outer sh.e.l.ls of the multi-colored, mutated Scarlet Blood Rice. He poured all the liquid into a gourd and stored it for the time being. He wanted to observe the effects and use the same amount every time, so he needed to do things properly during the preliminary preparations.

Because Gu Zuo maintained enough distance beforehand and the speed he collected the poisonous fluid was sufficiently fast, the test subjects weren't infected in advance from smelling the odor. At this time, he took the gourd and walked in front of them.

He started from the Xiantian stage one martial artist…

After taking the poisonous fluid, the martial artist's qi and blood faded very quickly. Almost in the blink of an eye, that Xiantian stage one martial artist's qi and blood had already dried up and he died! He wasn't even able to react to it!

Gu Zuo was gobsmacked.

He never expected that this kind of thing could happen!

Could it be that it was because the quant.i.ty of poisonous fluid he used was too much?

At this moment, Gu Zuo suddenly discovered a problem.

His experience was still too lacking… He unexpectedly forgot — If, during the process of the experiment, a test subject was damaged and the conclusion wasn't obtained, what should be done?

After rubbing his face, he forced a smile and went to the doorway.

He said to the disciple token: "Please supply me with another Xiantian stage one martial artist."

Fortunately, Elder Huo told Gu Zuo before he departed that if he had any other needs, he could use this method to inform the guards in the Black Prison. The need right now was to increase the number of test subjects to be used by him.

After that, Gu Zuo discovered the numbers on the disciple token had changed. It promptly decreased by ten contribution points. Meanwhile, the ground split open once more and a new metal berth appeared in front of him.

This time, Gu Zuo didn't dare act negligently as he tested.

Currently, a low-level martial artist was still okay. If it was an even higher leveled one… His contribution points were already dangerously low.

This one experiment took quite a few hours.

Gu Zuo used fresh water to dilute the poisonous fluid. He fed each grade of martial artist, one by one, and observed their reactions. Once the bulk of their qi and blood eroded, he stuffed them with top grade Rejuvenation Pills, Qi Generating Pills, and Snowy Ginseng Pills. This made their bodies constantly recover in short periods of time.

Merely, in Gu Zuo's storage s.p.a.ce, the amounts of a.n.a.logous pills that remained weren't considered too high — Most of them were the ones he had set aside for Gongyi Tianheng. However, it was fortunate that he had the habit of h.o.a.rding medicinal herbs. In the region of his storage s.p.a.ce that had medicinal ingredients, he had lots of the corresponding herbs.

At this moment, the Fire Essence Stone that Xu Lingxiu gave Gu Zuo was given a try. He threw it into the rank five Earth Fire, and discovered that the Earth Fire had gained a stronger spiritual nature and heated up even faster. This saved a lot of time.

Gradually, more and more experimental data was collected by Gu Zuo.

The true colors of the mutated Scarlet Blood Rice were also being revealed before Gu Zuo…

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